extension methods with generics - when does caller need to include type parameters?
- by Greg
Hi,
Is there a rule for knowing when one has to pass the generic type parameters in the client code when calling an extension method?
So for example in the Program class why can I (a) not pass type parameters for top.AddNode(node), but where as later for the (b) top.AddRelationship line I have to pass them?
class Program
{
static void Main(string[] args)
{
// Create Graph
var top = new TopologyImp<string>();
// Add Node
var node = new StringNode();
node.Name = "asdf";
var node2 = new StringNode();
node2.Name = "test child";
top.AddNode(node);
top.AddNode(node2);
top.AddRelationship<string, RelationshipsImp>(node,node2); // *** HERE ***
}
}
public static class TopologyExtns
{
public static void AddNode<T>(this ITopology<T> topIf, INode<T> node)
{
topIf.Nodes.Add(node.Key, node);
}
public static INode<T> FindNode<T>(this ITopology<T> topIf, T searchKey)
{
return topIf.Nodes[searchKey];
}
public static void AddRelationship<T,R>(this ITopology<T> topIf, INode<T> parentNode, INode<T> childNode)
where R : IRelationship<T>, new()
{
var rel = new R();
rel.Child = childNode;
rel.Parent = parentNode;
}
}
public class TopologyImp<T> : ITopology<T>
{
public Dictionary<T, INode<T>> Nodes { get; set; }
public TopologyImp()
{
Nodes = new Dictionary<T, INode<T>>();
}
}
